United States Patent
`Mason et al.
`
`[75]
`
`[54] PBX AUTOMATIC NUMBER
`IDENTIFICATION SYSTEM
`Inventors: Rodney Robert Maxon; Henry Au(cid:173)
`gust Meise, Jr., both of Boulder,
`Colo.
`[73] Assignee: Bell Telephone Laboratories, Incor(cid:173)
`porated, Murray Hill, N.J.
`Nov. 12,1971
`[22] Filed:
`[21] Appl. No.: 198,217
`
`179/18 FH
`[52] U.S. Ci
`H04q 3/72
`[51]
`Int. CI
`179/18 F H, 18 D, 18 D A,
`[58] FieldofSearch
`179/27 D B, 27 CB, 18 B D, 18 BE
`
`[56]
`
`References Cited
`UNITED STATES PATENTS
`3,346,700 10/1967 Anderson etal
`
`179/27 DB
`
`3,725,596
`tin
`[45] Apr. 3,1973
`
`Primary Examiner— Kathleen H. Claffy
`Assistant Examiner—Kenneth D. Baugh
`Attorney—R. J. Guenther et al.
`
`ABSTRACT
`[57]
`A PBX is disclosed having equipment for automati(cid:173)
`cally generating and transmitting calling station and
`trunk number information to a central office on out(cid:173)
`going calls. The disclosed system is an improvement in
`the art in that it does not require additional equip(cid:173)
`ment, such as matrices, for generating the number in(cid:173)
`formation. Instead, it obtains this information from
`pre-existing system circuitry which generates the same
`information in order to control the establishment of
`the network paths required for the serving of these
`calls.
`
`18 Claims, 12 Drawing Figures
`
`104'
`
`SUPERVISION
`141 T
`
`DIAL' 9
`DETECTOR
`-152
`
`MTR
`
`I
`
`T,R,S,C—j
`REGISTER
`0
`^I52A
`
`CODE
`TRANSL.
`151
`
`
`
`COUNTER COUNTER
`
`N50
`
`T.R.S.C— -j
`153
`L_
`REGISTER CONTROL
`REQUEST
`DELAY CCT.
`
`140
`
`TO OTHER _ \
`RT
`REGISTERS
`
`TO OTHER
`REGISTERS
`
`_\
`"MTR
`
`TOR'
`FOR1
`
`RDA'
`'DRA
`
`,107
`
`F.G
`
`H07
`
`— TO
`OTHER
`REGS
`
`LINE
`SCANNER
`
`H
`
`,113
`COMMON
`CONTROL
`
`GATE
`OUTPUT
`SIGNAL
`TRANSL-
`
`R0
`
`— J AN
`T9 TO TN
`REGISTER
`I
`TRUNK SCANNER
`^120
`rSSICA -
`SCANNER
`_£0_N_
`B0L
`143"
`
`J~~I44
`
`REGISTER
`BID CCT.
`
`MOT-
`
`,M0TI
`
`TRUNK
`BID CCT
`7
`I30A
`119
`
`A NI
`CONTROL
`CCT
`130 T
`
`J--.-14 6
`
`J-~ (V 3
`
`J--I47
`
`[— 74
`
`PG
`
`AN i B
`
`A NI E
`
`OTI-i
`
`MODE CCT.
`
`116'
`
`171
`115
`
`SLIO'
`
`5L89
`
`172'
`
`Page 1 of 18
`
`Voip-Pal Ex. 2046
`IPR2016-01201
`
`

`

`CD
`CD
`
`cai
`
`Qui
`
`—a
`
`-REGISTERS
`TO OTHER
`
`T.R.S.C
`
`PG
`T,R,S,C
`T,R,S,C
`
`REGISTERS
`TO OTHER
`
`HV
`
`NETWORK
`SWITCHING
`
`T.R.S.C
`
`T.R.S.C
`
`T,R,5,C
`
`IA
`
`FIG.
`
`Page 2 of 18
`
`

`

`CD
`CD
`ui
`en
`ro
`
`GO
`
`-J
`
`ro
`
`140
`
`DELAY CCT. h
`REQUEST
`
`REGISTER CONTROL
`
`153
`r.R.s.c-
`
`1
`
`\
`\
`COUNTER
`COUNTER
`
`i
`i
`
`i
`i
`
`TRANSL.
`CODE
`
`DETECTOR
`DIAL 9
`
`/-I52A
`
`T.R.S.C-^l
`
`REGISTER 0
`
`141
`7
`
`104-
`
`SUPERVISION
`
`FIG. IB
`
`Page 3 of 18
`
`

`

`CD
`CD
`en
`en
`ro
`
`OJ
`
`FIG. ID
`
`FIG. IB
`
`FIG. IC
`
`FIG. IA
`
`IF
`
`FIG.
`
`CO
`
`-J
`
`OJ
`
`OTI
`
`TRUNK CCT.
`INTERCOM
`
`114-N
`
`MOTI-
`
`-MOT
`
`TN
`
`T,R,S,C*
`T.R.S.C
`
`•TO CENTRAL OFFICE
`
`T.R
`
`MTG
`
`_2i
`
`TO,
`
`SUPERVISION
`-154
`
`5
`fUi
`TRUNK CCT. 0
`CENTRAL OFFICE
`114-0
`
`T.R.S.C
`
`TO CENTRAL OFFICE
`
`TRUNK CCT. 9
`CENTRAL OFFICE
`L 114-9
`
`/T9
`T.R.S.C
`
`IC
`
`FIG.
`
`Page 4 of 18
`
`

`

`CD
`CO
`CJl
`en
`r\)
`
`CO —J
`
`OJ
`
`CO
`
`—o
`
`136
`
`CO.
`TO
`
`J
`
`^ 158
`
`-135
`
`NUMBER
`i NUMBER
`STATION | TRUNK
`NUMBER STORE REG.
`
`i
`
`H>TC9
`
`/TO
`
`_d9_
`
`TRUNK CODE TRANSLATOR^
`
`lOTI
`
`148
`
`READOUT CCT.
`
`-162
`
`-163
`
`-DATA
`
`!65-
`READOUT
`START
`
`STATION CODE TRANSLATOR
`
`,SCN
`
`BID & DATA
`
`MK36B
`COMMAND
`
`l|36A
`
`LINK
`DATA
`1_
`175
`
`BID
`
`^164
`
`ANI CCT.
`
`131
`
`•132
`
`SUPERVISION AND SEQUENCE CONTROL
`
`ANIBi
`FIG. ID^
`
`Page 5 of 18
`
`

`

`CD
`CD
`ui
`cn
`no
`"-•J
`CO
`
`CO
`
`-a
`
`* 3.337, 432
`U.S. PATENT
`
`ANI CCT.
`
`TO
`
`ANIE
`
`BID CCT
`TO TRUNK
`
`tn
`
`ANI CCT.
`
`ANIB FROM
`
`REGISTER REQUEST
`
`TO
`
`DRA
`DELAY CCT.
`
`FIG. 3
`
`FIG 2
`
`Page 6 of 18
`
`

`

`*3,377, 432
`U.S. PATENT
`
`ABBOTT ET AL
`
`FIG.18
`
`RST
`
`CONTROL CCT
`FROM ANI
`
`FIG. 2
`
`DRA-
`
`-RDA
`
`ABBOTT ET AL
`
`FIG. 17
`
`RO U T R
`COUNTER
`
`ABBOTT ET AL
`
`FIG. 27
`
`ABBOTT ET AL
`
`FIG. 26
`
`FOR
`
`FORI^U
`
`RDSE
`
`RO
`
`RST
`
`RDS
`
`RDO
`RD FF
`
`TDE
`
`TDI
`
`C2
`
`D2
`
`TDOx
`
`REGISTER REQUEST DELAY CCT.
`
`FIG. 3
`
`• FOR
`
`-FORA
`
`FOR
`
`R3'
`
`DRO
`
`FOR
`
`Page 7 of 18
`
`

`

`PATENTED APR3 1973
`
`3 , 7 2 5 , 5 96
`
`SHEET 7 OF 7
`
`FIG. 4 A
`
`Rl
`1 o VW—
`R2
`2 o——'WV—'
`r'n
`VW—1
`
`No
`
`FIG. 4C
`INVERTING
`AND GATE
`
`FIG. 4 B
`INVERTING
`OR GATE
`
`FIG. 4D
`INVERTER
`
`FIG. 4E
`FLIP-FLOP
`
`Page 8 of 18
`
`

`

`3,725,596
`
`4Q
`
`
`
`t
`
`r u nk
`
`1 Q0
`
`y
`
`s t
`
`a t
`
`i on
`
`
`
`u s
`
`er
`
`
`
`r
`
`e m o
`
`v
`
`es
`
`
`
`is
`
`
`
`c
`
`o
`
`n
`
`n
`
`e
`
`c
`
`t
`
`ed
`
`
`
`to
`
`a
`
`IDENTIFICATION
`
`2
`1
`Our invention is disclosed as embodied in a PBX hav-
`PBX AUTOMATIC NUMBER
`ing an end marked network together with a wired logic
`SYSTEM
`system controller. An outgoing call is initiated when a
`_
`n is ^ t,
`r e.
`BACKGROUND OF THE INVENTION
`5 gister, and dials a prefix digit, such as 9, to obtain a
`1. Field of the Invention
`connection to a central office trunk circuit. The re-
`This invention relates to a telephone system and, in
`gister detects the dialing of the prefix digit 9 and ad-
`particular, to a private branch exchange (PBX) system
`vises the system controller that a connection to an out-
`having equipment for automatically identifying the
`going trunk circuit is required.
`calling station and trunk used on calls outgoing to a
`In accordance with our invention, the controller
`central office.
`determines whether the ANI equipment is idle before it
`2. Description of the Prior Art
`proceeds further in serving the call. If the ANI equip-
`It is common practice to provide automatic number
`ment is available, the controller causes a trunk scanner
`identification (ANI) equipment in a PBX which trans-
`to select an idle outgoing trunk circuit and, at the same
`mits information to a central office identifying the
`calling station and trunk number. A typical prior art ar- 15 time, causes a line scanner to identify the calling line
`rangement for performing this function is shown in the
`circuit. When the trunk and line scanners have per-
`U.S. Pat. No. 3,346,700 to H. P. Anderson et al of Oct.
`formed their required functions, the controller causes
`10, 1967. In the Anderson et al system, the ANI opera-
`the network appearances of the identified calling line
`tion is performed by equipment which, after the calling 2Q
` circuit and the selected outgoing trunk circuit to be
`station and the selected outgoing trunk are connected
`marked. The network then establishes a connection
`by the PBX switch train, transmits an identification
`between the two circuits. Immediately subsequent to
`pulse to the trunk circuit and back through the switch
`the establishment of this connection, the scanners
`train to the calling line circuit. This pulse is applied by
`transmit station and trunk number information to ANI
`the line circuit to a station number matrix which j5 equipment at the PBX. Subsequently, in the same
`generates an output signal identifying the calling sta-
`manner as described in the Anderson et al patent, the
`tion. The outgoing trunk circuit is identified by other
`A NI information is transmitted to the central office
`matrix equipment when the call is extended to the cen-
`over a path separate and apart from the voice path over
`tral office. The station number and trunk number
`which the call itself is extended to the central office,
`matrices cooperate with the remainder of the provided 30
`The use of the line circuit and trunk circuit scanners
`equipment to transmit the station and trunk number in-
`for generating the information required to establish the
`formation to the central office over a data channel that
`network path, as well as for supplying the same infor-
`is separate from the voice path used on the connection.
`mation to the ANI equipment, eliminates the necessity
`Although the ANI system of Anderson et al operates
`of providing the special equipment that is required in
`satisfactorily to provide the required information, its 35 the prior art ANI systems.
`cost and complexity is increased by its use of specially
`As already mentioned, the system controller first
`provided equipment including the station number and
`determines whether the ANI facilities are idle and
`trunk number matrices.
`available before it effects the establishment of a net¬
`.
`work path between a calling line and a central office
`BRIEF SUMMARY OF THE INVENTION
` P,f
` t he ANI facilities are available, the connection
`It is, therefore, an object of the invention to provide
`is established and the ANI information is generated and
`improved automatic number identification equipment
`transmitted to the central office. If, however, the con-
`in a private branch exchange.
`troller determines that the ANI facilities are busy and
`It is a further object to provide automatic number
`thus are not immediately available, it advises the re-
`identification equipment that is of lesser cost and com- 45 gister to wait and delay the call for a short period of
`plexity than the prior art arrangements.
`time such as, for example, 100 milliseconds. The con¬
`troller then releases and serves other calls during this
` m ii i i s ec o nd interval. After 100 milliseconds, the
`SUMMARY DESCRIPTION
`register requests the services of the controller and
`The prior art ANI systems are less than ideal since
`they require the use of specially provided equipment to 50 again advises it that an outgoing trunk connection is
`generate the calling line and trunk number informa-
`required for a central office call.
`tion. Thus, Anderson et al requires the use of special
`If the controller determines that the A NI facilities
`matrices. The provision of this additional equipment is
`are now available, the call is served as already
`philosophically superfluous since most systems already
`described. If the ANI facilities are still busy, the register
`contain equipment, e.g., a network controller, for
`is instructed to wait for another 100 millisecond inter-
`identifying the circuits involved on each call connec-
`val. In accordance with our invention, the register will
`tion. The controller obviously has this capability since
`wait for as many 100 millisecond intervals as may be
`it could not otherwise control the establishment of a
`required for the ANI facilities to become available,
`network connection between a calling line and an out- When the ANI equipment finally does become availa-
`going trunk.
`ble, the line and trunk number information is obtained
`We provide an ANI system which does not require
`from the line and trunk scanners, respectively, applied
`additional equipment
`to generate line and
`trunk
`to and stored in the ANI equipment at the PBX, and
`number information. Instead, our system obtains this
`transmitted by it to the central office as already
`information from the system controller at the time the 65 described.
`controller governs the establishment of a network con-
`The circuitry of our invention restores the ANI facili-
`nection between a calling line circuit and an outgoing
`ties to their idle state whenever an equipment malfunc-
`PBX trunk circuit on a central office call.
`tion is detected that might otherwise cause the facilities
`
`Page 9 of 18
`
`

`

`3,725,596
`
`4
`FIG. 4E illustrates how two OR gates of the type
`shown on FIG. 4B may be interconnected to form a
`flip-flop.
`
`5
`
`DETAILED DESCRIPTION
`
`3
`to remain indefinitely in a busy state. This insures that a
`register serving a central office call will not wait in(cid:173)
`definitely for the availability of inoperable ANI equip(cid:173)
`ment.
`A feature of our invention is the provision of cir(cid:173)
`cuitry which controls the establishment of a network
`path between a calling line circuit and a selected trunk
`circuit and, at the same time, uses the network control
`information to supply calling line and trunk number in(cid:173)
`formation.
`A further feature is the provision of a line scanner to
`identify a calling line circuit, a trunk scanner to select
`an idle trunk circuit, and equipment which uses output
`signals generated by the scanners to control the
`establishment of a network path between the two cir(cid:173)
`cuits as well as to generate line number and trunk
`number information for ANI equipment.
`A further feature is the provision of facilities for
`scanning idle trunk circuits to select an idle circuit for
`use on a call, facilities for scanning line circuits to
`identify a line circuit requesting a connection to an out(cid:173)
`going trunk circuit, and facilities for using signals
`generated by the scanning to control the establishment
`of a network path between the identified line circuit
`and the selected trunk circuit as well as to transmit line
`and trunk number information to a central office to
`which the call is extended.
`A further feature is the provision of a register for de(cid:173)
`tecting the dialing of a prefix digit for an outgoing cen(cid:173)
`tral office call, and with facilities for causing the re(cid:173)
`gister to delay further serving of the call for a predeter(cid:173)
`mined period whenever ANI equipment is not available
`for use on the call.
`A further feature is the provision of a register for de(cid:173)
`tecting the dialing of an outgoing call prefix digit, facili(cid:173)
`ties for determining the idle-busy status of ANI equip(cid:173)
`ment, facilities for completing a network path between
`the calling line circuit as an idle trunk circuit if the ANI
`facilities are idle, and facilities for temporarily suspend(cid:173)
`ing further service of the call whenever the ANI equip(cid:173)
`ment is currently busy.
`A further feature is the provision of circuitry which
`permits central office calls to be completed even
`though the A NI equipment may be inoperable due to
`an equipment malfunction.
`DRAWING
`These and other objects and features of the invention
`will become more apparent upon a reading of the fol(cid:173)
`lowing description thereof taken in conjunction with
`the drawing in which:
`FIGS. 1A, I B, I C, and I D, when arranged as shown
`on FIG. IE, disclose a specific illustrative embodiment
`of our invention;
`FIG. 2 discloses additional details of the ANI control
`circuit;
`FIG. 3 discloses additional details of the register
`request delay circuit;
`FIG. 4A discloses the details of a basic transistor
`logic circuit;
`FIG. 4B illustrates the symbol used when the circuit
`of FIG. 4A is operated as an inverting OR gate;
`FIG. 4C illustrates the symbol used when the circuit
`of FIG. 4A is operated as an inverting AND gate;
`FIG. 4D illustrates the symbol used when the circuit
`of FIG. 4A is operated as an inverter; and
`
`35
`
`L O G IC G A T ES - F I G S. 4A, 4B, 4C, 4D, and 4E
`The disclosed system makes extensive use of
`transistor resistor
`logic circuits in which a single
`10 transistor stage is used as an inverter, an inverting AND
`gate, or an inverting OR gate, depending upon the na(cid:173)
`ture of the input signals applied thereto and the func(cid:173)
`tion to be performed by the stage. FIG. 4A discloses a
`schematic of a circuit which comprises a single NPN
`15 transistor, a collector resistor RC, and a plurality of
`input resistors, Rl - RN. The circuit of FIG. 4A is basi(cid:173)
`cally a single-stage inverter since a positive going signal
`applied to the base appears as a negative going signal at
`the collector, and vice versa.
`20 The stage may be used as an inverting OR gate, as
`shown in FIG. 4B, by leaving the circuit normally cut
`off, i.e., all inputs LOW (ground). In this case, a posi(cid:173)
`tive going signal applied to one or more input leads will
`turn the transistor ON and provide a negative going
`signal on the collector. The stage also may be operated
`as an inverting AND gate as shown on FIG. 4C. In this
`case, the transistor is normally held ON by a positive
`signal applied to one or more of its inputs. The AND
`condition of the circuit occurs when a ground potential
`is applied to all inputs. This turns the transistor OFF
`and produces a positive going signal at its output.
`The circuit of FIG. 4A may also be operated as a sin(cid:173)
`gle input inverter as shown on FIG. 4D.
`FIG. 4E discloses the symbol used when two inverter
`gates of the type shown in FIG. 4B are interconnected
`and operated as a flip-flop. The flip-flop is said to be in
`a set state when the upper gate is conducting and in a
`reset state when its lower gate is conducting. The out-
`40 put conductor of a conducting stage is LOW; the out(cid:173)
`put conductor of a nonconducting stage is at a HIGH
`potential. The flip-flop is switched from one state to the
`other by momentarily applying a HIGH potential to the
`input of the nonconducting stage.
`GENERAL DESCRIPTION - FIGS. 1A, IB, and IC
`FIGS. 1A, I B, IC, and I D, when arranged with
`respect to each other as shown in FIG. IE, disclose a
`specific embodiment of our invention. The invention is
`50 disclosed as embodied in a wired logic electronic type
`PBX of the type disclosed in detail in the U.S. Pat. No.
`3,377,432 to H. H. Abbott et al of Apr. 9, 1968. The
`Abbott et al specification is hereby incorporated as a
`part of the present specification to the same extent as if
`fully set forth herein.
`The system comprising our invention includes an end
`marked network which is designated as element 112 on
`FIG. 1A. It further includes a plurality of PBX stations
`ST10 through ST89 each of which is connected to one
`of line circuits LCIO through LC89. Each line circuit is
`connected to the switching network 112 and is addi(cid:173)
`tionally connected by means of various conductors to
`common control 113 on FIG. IB. These conductors in-
`65 elude a set of code leads 107, conductors F and G, and
`an SL- conductor for each line circuit such as conduc(cid:173)
`tor SLIO for line circuit LC10. As subsequently
`described, the code leads permit common control to
`
`45
`
`55
`
`Page 10 of 18
`
`

`

`j ^
`
`30
`
`
`
`3,725. 596
`
`6
`5
`vice request from a calling line circuit, the identifica(cid:173)
`scan and identify the various line circuits; the SL- con(cid:173)
`tion of a calling line circuit requiring a connection to a
`ductors permit common control to receive signals from
`register, the selection of a called line circuit following
`the line circuits indicating their current conductive
`the registration of a called number, the selection of a
`states.
`trunk circuit, and the identification of a calling line cir(cid:173)
`The disclosed embodiment also includes a plurality 5
`cuit at the time it is to be connected to the selected
`of registers, such as register 104. It further includes a
`trunk circuit, and in turn, to the called line circuit.
`plurality of central office trunk circuits 114—0 through
`114-9, and an intercom trunk circuit 114-n. The line
`Common control includes a line circuit scanner 116
`circuits are connected to the left side (the line side) of
`having a plurality of output positions which are con(cid:173)
`the network; the trunk circuits are connected to the ^
`nected by the code leads 107 to the line circuits. Each
`right side (the trunk side) of the network. Each register
`line circuit is connected to a unique combination of
`has both a line side and a trunk side appearance in
`codes leads. Common control also includes a gate out(cid:173)
`order that it may be connected via the network to a
`put signal translator 117 which is connected to conduc(cid:173)
`trunk circuit on an incoming call or to a line circuit on
`tors SL10 through SL89 of the line circuits. Element
`an outgoing or intra-PBX call. The switching network is
`117 translates the signals received from the line circuit
`of the end marked type and in response to the presence
`gates and informs common control regarding the cur(cid:173)
`of a marking potential on each side
`thereof, it
`rent status of a call served by a line circuit. Common
`establishes independently of the remainder of the
`control also includes a register bid circuit 118 and a
`system, a network interconnection between the circuits 20
`trunk bid circuit 119 which receive signals from the re(cid:173)
`associated with the marked terminals.
`gisters and trunk circuits, respectively, at the time these
`circuits require the service of common control. Com(cid:173)
`The disclosed system is of the common control type
`mon control also includes a register and trunk scanner
`in which the common control 113 governs the order in
`120 whose function is to select an idle register or an
`which the various circuits are interconnected via the
`idle trunk circuit for connection to a line circuit.
`network during the serving of each call. Common con- 25
`trol receives call service requests from the line circuits,
`The system of FIG. 1 further includes an ANI control
`from the registers, and from the trunk circuits. Upon
`circuit 130 within common control, a request delay cir(cid:173)
`the receipt of each request, common control sets its
`cuit 140 within the register, and an ANI circuit 131.
`mode circuit 115 to a state unique to the request. The
`The function of the ANI circuit 131 is to transmit line
`mode circuit and common control together regulate
`and trunk information over path 136 to a central office
`the operation of the requesting circuit, as described in
`on each call extended by the PBX to the central office
`the Abbott et al patent, and control the establishment
`by one of trunk circuits 114-0 through 114-9. The
`of the network connection between the requesting cir(cid:173)
`manner in which the system of FIGS. 1, including the
`cuit and any circuit of the system with which the
`ANI circuit 131, performs this function is subsequently
`requesting circuit must be connected. The serving of a ^
`described in detail.
`call may require a plurality of network connections to
`SPECIFIC DETAILED DESCRIPTION
`be established sequentially.
`Each line circuit includes a transistor gate which is
`NORMAL SYSTEM OPERATION
`selectively controlled to assume either an ON or an ^
`The operation of the system of FIGS. 1 for the serv(cid:173)
`OFF conductive state. A gate is said to be ON when(cid:173)
`ing of calls that do not require the use of the ANI facili(cid:173)
`ever it receives an energizing potential at its input (its
`ties is fully described in detail in the Abbott et al
`base), and is said to be OFF when no energizing poten(cid:173)
`patent. Therefore, the following only briefly describes
`tials are applied to its input. The conductive state of a
`how such calls are served. An understanding of the
`gate, such as Gate G10 in line circuit LC10, is con- 45
`system operation for the serving of these calls will
`trolled by energizing potentials received from the G
`facilitate an understanding of how calls requiring an
`and F leads as well as from code leads 107. Each poten(cid:173)
`ANI operation are served. The following description is
`tial source is effective by itself to maintain a line circuit
`made with the assumption that station ST10 initiates a
`gate ON, independent of the other source. A potential
`call that is to be extended to a central office via trunk
`is applied to the S lead of a line circuit at certain times 50
`circuit 114-0.
`and is effective to cancel the energizing potential
`Common control supplies energizing potentials over
`received over the G and F leads. This causes the line
`the F and G leads to hold the transistor gate G10 ON
`circuit's gate to turn OFF, provided it is not at the same
`during the idle state of line circuit LC10. An off-hook
`time receiving an energizing potential over one of the
`condition at calling station ST10 causes the off-hook
`code leads. The code leads are also connected to the 55
`detection circuitry of the line circuit to cancel this
`register so that it may at certain times control the con(cid:173)
`potential and to turn its transistor OFF. This causes a
`ductive state of the line circuit gates.
`change of state signal to be transmitted over conductor
`Signals indicating the conductive state of each line
`SL10 to the gate output and signal translator 117 to ad(cid:173)
`circuit gate are transmitted over the SL- conductors to
`vise it that one of the
`line circuits is currently
`common control. These signals enable common control ^
`requesting service. In response to the receipt of this
`to monitor the ON and OFF state of each line circuit
`signal, and as described in the Abbott et al patent, com(cid:173)
`gate and, in turn, by means of prewired logic, to deter(cid:173)
`mon control initiates a scanning of all line circuits by
`mine whether a line circuit requires action by the com(cid:173)
`means of scanner 116 and its code leads 107. The
`mon control with regard to either a call initiated by or ^
`transistor gate in the calling line circuit is switched ON
`directed to the line circuit. Included among the func(cid:173)
`when the scanning begins and is switched OFF when
`tions performed by common control in connection with
`the calling line circuit is scanned. A change of state
`the establishment of calls are the recognition of a ser-
`
`Page 11 of 18
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`3,725,596
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`7
`signal is transmitted over signal lead SLIO to the gate
`output and signal translator 117 whenever the gate of
`line circuit LC10 switches its conductive state. The
`turn OFF of the gate G10 when it is scanned transmits a
`signal over conductor SLIO to stop the scanner in its
`operative position associated with line circuit LC10.
`Common control now initiates the sequence of ac(cid:173)
`tions required to select an idle register. A register is
`selected by the register and trunk scanner 120 which
`has an operative position for each register or trunk cir(cid:173)
`cuit and which also has an output conductor extending
`from each of its positions to the register or trunk circuit
`with which the position is associated. The scanner out(cid:173)
`put conductors are designated RO through Rn and TO
`through Tn. The R- conductors extend to the registers;
`the T- conductors extend to the trunk circuits. Thus,
`output conductor RO extends from the scanner to re(cid:173)
`gister 0; output conductor TO extends from the scanner
`to trunk circuit 0.
`The mode circuit 115 together with common control
`initiates the selection of a register by applying poten(cid:173)
`tials to conductors 143 and 146. These conductors ex(cid:173)
`tend from the mode circuit to scanner control 111 and
`to the register bid circuit 118, respectively. The register
`bid circuit responds to the potential on conductor 146
`and applies an enable potential to conductor MTR
`which extends to all registers. With respect to register
`0, it extends to input 2 of AND gate MTR which con(cid:173)
`trols the selection and seizure of the register as
`described in Abbott et al.
`A register can be seized only when all input conduc(cid:173)
`tors of its MTR AND gate are enabled. Input 1 of gate
`MTR extends to supervision circuit 141 of the register.
`This input is enabled whenever the register is idle.
`Input 2 extends to the enable conductor MTR; input 3
`extends to scan conductor RO. Thus, assuming that re(cid:173)
`gister 0 is currently idle, input 1 of its MTR gate is cur(cid:173)
`rently enabled by the supervision circuit. Input 2 of the
`gate is now enabled by the MTR conductor from the re(cid:173)
`gister bid circuit. This leaves the conductive state of the
`gate under control of its input 3 which is connected to
`conductor RO of the scanner.
`The potential on the conductor 143 activates gate
`SSICA in the scanner control circuit 111. This, in turn,
`activates scanner 120 which begins a scanning opera(cid:173)
`tion of the register and trunk circuits. When register 0
`is scanned, the enable potential on conductor R0 turns
`OFF gate MTR to effect a seizure of the register in the
`manner described in Abbott et al. The turn OFF of gate
`MTR applies a signal to conductor RT which extends
`back to the scanner control circuit 111. The receipt
`and this signal by gate SSICA stops the scanner 120 in
`its position associated with register 0. The signal on
`conductor RT also advises common control that ah idle
`register has been selected and that the next sequence of
`operations required to serve the call may now be in(cid:173)
`itiated.
`Next, common control causes the register to mark its
`C lead trunk side appearance and also causes the line
`circuit LC10 to mark its C lead network appearance.
`The end marked network then completes a path
`line circuit LC10 and register 0 without
`between
`further assistance of common control.
`The calling party at station ST10 now dials a prefix
`digit, such as the conventional prefix digit 9, to initiate
`
`8
`an outgoing call to the central office. The digit 9 is re(cid:173)
`gistered by counter 150 within the register, translated
`by code translator 151, and detected by the dial 9 de(cid:173)
`tector 152. Upon the detection of this digit, the register
`5 control circuit 153 advises common control that the
`digit 9 has been dialed for a central office call.
`Common control initiates the sequence of circuit ac(cid:173)
`tions required to select and seize an idle outgoing trunk
`circuit. Let it be assumed that trunk circuit 114-0 is idle
`,u and is selected for use on this call. The selection of this
`circuit is controlled by its gate MTG which functions in
`a manner analogous of gate MTR for the register. Input
`1 of the gate is enabled by the supervision circuit 154
`whenever the trunk circuit is idle. Input 2 of the gate is
`' ^ connected to scan conductor TO; input 3 is connected
`to the group enable conductor MOT which extends to
`all central office trunk circuits in common. This con(cid:173)
`ductor is connected to trunk bid circuit 119 and it is
`2Q enabled whenever common control is in the process of
`selecting an idle central office trunk circuit.
`At this time, common control applies potentials to
`conductors 147 and 143 to enable conductor MOT and
`to initiate a scan of the trunk circuits, respectively.
`25 Gate MTG turns OFF and effects a seizure of trunk cir(cid:173)
`cuit 114-0 when conductor MOT is enabled and the
`trunk circuit is scanned by an enable potential on con(cid:173)
`ductor TO. The turn OFF of gate MTG applies a signal
`to conductor OT1 extending to common control. The
`30 receipt of this signal stops scanner 120 in its operative
`position associated with the trunk circuit. It also ad(cid:173)
`vises common control that an outgoing trunk circuit
`has been seized and that common control may there(cid:173)
`fore
`initiate the next sequence of circuit actions
`35 required for serving the call.
`After trunk circuit 114-0 is selected, common con(cid:173)
`trol initiates a register call-back operation so that the
`line scanner 116, together with other circuitry in com(cid:173)
`mon control, can identify the line circuit currently con-
`40 nected to register 0, i.e., line circuit LC10. Common
`control (1) causes the gates in all line circuits to be
`held ON only by a potential applied to the F lead, and
`(2) causes the register to apply a negative call-back
`potential to its trunk side sleeve lead. This potential is
`45 transmitted through the network to the sleeve lead of
`line circuit LC10. Scanner 116 now begins a new line
`scanning operation. In the same manner as before, gate
`G10 of line circuit LC10 turns OFF when it is scanned
`and transmits a signal over conductor SL10. Common
`50 control receives this signal and (1) causes the register
`to release, (2) causes trunk circuit 119-0 to mark its C
`lead network appearance, and (3) causes line circuit
`LC10 to mark its C lead network appearance. As
`described in Abbott et al, the network responds to
`55 these marks and completes a connection from calling
`station ST10 to trunk circuit 114-0. A forward seizure
`signal is then extended over the T and R conductors to
`the central office. The central office recognizes the
`receipt of the call from the PBX and applies dial tone
`back to the connection to advise the calling party at
`station ST10 that he may dial the additional digits
`required to complete the call. In normal system opera(cid:173)
`tion, the preceding described operations are effected at
`65 a sufficiently rapid rate so that the calling party nor(cid:173)
`mally receives the second dial tone (the dial tone pro(cid:173)
`vided by the central office) soon after dialing of the
`prefix digit 9 into the PBX equipment.
`
`Page 12 of 18
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`3,725,596
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`the input of translators 133A and 134A which translate
`the received information into a form suitable for the re-
`gister 135. The translated station number information
`\s applied over path 157 to the station number portion
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